PS Is an 87 Yo M Admitted to the Hospital

PS is an 87 yo M admitted to the hospital for failure to thrive.While hospitalized, a physician has determined that PS also has megaloblastic anemia.
-Given PS's history, what is a likely cause of the megaloblastic anemia?

A) reduced folate synthesis
B) reduced iron absorption
C) reduced B12 due to inadequate intrinsic factor
D) reduced intrinsic factor due to inadequate B12